Support ASN dot notation.

inventory_provider/juniper.py

@@ -252,12 +252,25 @@ def asn_to_int(asn_string: str) -> int:
 
     Returns:
     int: ASN in integer format.
+
+    Raises:
+    ValueError: If the ASN string is not in the expected format or exceeds valid range.
     """
-    if '.' in asn_string:
-        high_order, low_order = map(int, asn_string.split('.'))
+
+    dotted_asn_pattern = re.compile(r'^(\d+)\.(\d+)$')
+    match = dotted_asn_pattern.match(asn_string)
+
+    if match:
+        high_order, low_order = map(int, match.groups())
+
+        if high_order > 0xffff or low_order > 0xffff:
+            raise ValueError(f'Invalid ASN format: {asn_string}. Both components must be <= 0xffff.')
+
         return (high_order << 16) | low_order
-    else:
+    elif asn_string.isdigit():
         return int(asn_string)
+    else:
+        raise ValueError(f'Unable to parse ASN string: {asn_string}. Expected either a pure integer or a dot notation.')
 
 
 def _system_bgp_peers(system_node):